The invention relates to a needle for loop-forming textile machines, in particular a transfer needle.
For loop-forming textile machines, transfer needles that are arranged to transfer a loop that has been received onto another needle are known.
From German Patent Disclosure DE 199 05 668 A1, one such transfer needle is known. It has a needle body with an elongated shank, which defines a needle back and needle side faces. The shank is subdivided into one high portion and one low portion. The high portion is provided on one side face with an indentation, which serves to receive an approximately rectangular fastening portion of a transfer spring. The rectangular portion is located in the pocket, and on its upper edge and lower edge it rests on the flanks of the packet. The depth of the pocket is slightly greater than the thickness of the fastening portion of the transfer spring. For securing the transfer spring in the pocket, swaged points can be provided. From this patent, a transition edge can also be found between the receiving pocket of the fastening portion of a transfer spring and the needle taper; this edge is needed so that a needle can penetrate between the needle shank and the transfer spring in order to take on a loop.
A similar transfer needle is known from German Patent DE 284 7972 C2. Once again, then needle shank is provided on its side face with an indentation, which receives the fastening portion of the transfer spring. Above and below the indentation, a striplike region of the side face or flank of the shaft of the transfer spring remains, which guides the needle in the needle track into which the needle is inserted.
It in also known, for instance from Japanese Patent Disclosure JP 59-211661, to place the transfer spring against a flat side of the needle shank, without providing the shank with an, indentation for receiving any fastening portion whatever. This is a specialized design that is not suitable for all knitting machines.
Fastening a transfer spring in a lateral recess of the needle shank is also known from Japanese Patent Disclosure JP 56-101960, JP 57-167797, and JP 6-38140.
In this design, a great deal of attention must be given to correctly fastening the transfer spring in the pocket. If the transfer spring comes loose, this can cause very serious problems.
With the above as the point of departure, it is the object of the invention to create a needle with a transfer spring that is retained on the needle in captive fashion in a simple, sturdy way.
This object is attained with a needle as defined by claim 1.
The needle of the invention has a needle body, which has two flanks for guidance in a needle track. A slit of elongated shape is embodied in the needle body and extends into the needle body between the two flat sides or flanks. The long side of the slit thus opens out at a narrow side of the needle body, preferably on its top side. The top side of the needle body is the side from which a butt protrudes and toward which a hook embodied on the end of the needle points. If needed, however, the slit can also open out at the needle back. The needle back is the narrow side that, when the needle is inserted into the needle track of a knitting machine, rests on the bottom of the needle track. The slit is open at its face end in the direction of the hook of the knitting machine needle.
Retaining the transfer spring in a slit disposed between the two flanks has the advantage that the flanks can be embodied as entirely or nearly entirely closed surfaces. Unlike the prior art, the flanks of the needle body rest over a large area on the side faces of the needle track. There is no open pocket here in which dirt such as oil, fiber residues, abraded material and the like could collect. In a needle according to the invention, the load-bearing part of the flank, which is disposed closer to the spring, is lengthened by the length of the pocket used in the prior art. As a result, both flanks of the needle body have a proportionally large load-bearing area. This leads to improved guidance of the needle shank, and as a result the lateral deflections of the needle that occur in operation are reduced. This in turn has advantageous effects on the operating properties of the needle of the invention. For instance, because there is less lateral deflection of the needle, the penetration of a needle that is taking on the loop into the space defined between the transfer sprig and the needle body is very secure. On the other hand, margins of safety and dimensional allowances can thus be reduced.
Because of the proportionally large load-bearing area of the flanks of the needle body, wear of the needles and of the side faces of the needle tracks can be reduced here. Moreover, because of the avoidance of collections of dirt in the lateral pockets that were provided earlier, the smooth running of the needles in the needle track can be assured.
In the needle of the invention, the transfer spring, as in conventional needles, is curved laterally away from the needle body during the transfer process by the needle, which is taking on the loop and which penetrates at an angle. The forces to be transmitted from the needle body by the fastening portion of the transfer spring are thus oriented at an angle to the needle body. One force component is oriented essentially perpendicular to the flat sides of the needle. In the needle of the invention, the slit in turn extends transversely or at an angle to these forces; that is, the fastening portion of the transfer spring is caught between two faces with regard to these forces. By comparison, the opening direction of the receiving pocket for the fastening portion of the transfer spring in the prior art essentially is the same as the direction of action of the forces. While the forces engaging the spring in the prior art thus put a burden on the swaged points or other fastening means that retain the fastening portion in the pocket, this is not the case in the needle of the invention. In the invention, any fastening means, such as welded points, soldered points, adhesively bonded points, swayed points, and the like, serve solely to prevent slipping or loss of the transfer spring in its slit, but the forces to be absorbed in the operation of the needle act precisely not upon the connection points but instead are intercepted over a large area. Because of how the slit is disposed in the needle body, the transfer spring is embedded with its fastening portion inside the needle body.
In a preferred embodiment of the needle of the invention, the depth of the slit is at least as great as the height of the anchoring portion of the transfer spring. As a result, the anchoring portion disappears entirely in the slit, or at least is flush with the plane of the top side of the needle. Preferably, the thickness of the anchoring portion of the transfer spring also matches the width of the slit. AS a result, the anchoring, portion of the transfer spring rests essentially without play in the slit. Force transmission over a large area is made possible.
Preferably, the depth of the slit exceeds half the height of the needle body. As a result, transfer springs with a high anchoring portion can be used, which permits secure fastening of the transfer spring in the slit.
The slit can in principle be embodied as continuous. Preferably, however, it has a bottom, either in the vicinity of the back side of the needle or in the vicinity of the top side of the needle. In this design, a stale needle body is obtained without excessive weakening.
For positioning and/or fastening the transfer spring, positive-engagement elements, for instance in the form of swaged points, or fastening points in the form of adhesively bonded, welded or soldered connections, can be provided. With them, the transfer spring can be positioned and/or fastened in the slit even if the depth or length of the slit has a relatively wide variation in production.
In the needle of the invention, the elongated inner edge of the slit pointing away from the spring is preferably disposed in the same plane as the outer face of the needle shank, in the region of the shanks taper. Hence there is no transitional edge between the receiving slit for the transfer spring and the end region of the shank taper for receiving a needle that is taking on a loop. Thus yet another point where dirt can collect and be deposited can be eliminated without substitution.
Further details of advantageous embodiments of the invention are the subject of the drawing, description, or dependent claims.